A body moves in a straight line but its motion during the first 15 s is not uniformly…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A body moves in a straight line but its motion during the first 15 s is not uniformly accelerated throughout. Instead, the motion can be viewed as a sequence of time intervals in each of which the acceleration is constant.
Answer the following questions with reference to such a situation.
(i) What is meant by treating a motion as a sequence of intervals with separate constant accelerations? State any one practical advantage of doing so.
(ii) Explain how the total displacement during the 15 s can be obtained when the acceleration in each interval is known to be constant.
(iii) A student records the velocity of the body at four instants and plots the following straight-line segments on a velocity–time graph:
Segment AB: 0–5s, velocity increases from 2m/s to 12m/s.
Segment BC: 5–9s, velocity remains 12m/s.
Segment CD: 9–15s, velocity decreases uniformly from 12m/s to 0m/s.
Describe (a) the nature of acceleration in each interval and (b) how you would determine the net displacement from the graph without using any kinematic equation.